Many different types and designs of vise assemblies for use with machinery, such as band saws, are known in the art. Vise assemblies typically comprise at least two opposed jaws defining a workpiece receiving and retaining channel, with at least one of the jaw members being laterally adjustable to effectuate clamping and releasing of the workpiece.
The vise assembly of the present invention is especially suitable for use with band saw apparatus for production cutting, and it is moreover particularly well suited for use as a movable or shuttle vise.
Conventional band saw apparatus generally utilize a stationary vise assembly mounted proximate the saw blade cutting stretch for clamping a workpiece in proximity to the desired cut. A shuttle vise assembly is positioned on a remote side of the stationary vise from the saw blade cutting stretch and reciprocates along a path perpendicular to the cutting stretch on a vise bench or feed table. The shuttle vise periodically advances a workpiece toward the cutting stretch for cutting of a series of cuts along the length of the workpiece. After each cut of the workpiece is complete, the shuttle vise assembly releases the workpiece and is displaced a predetermined distance away from the saw blade cutting stretch, the displacement distance corresponding to the desired cut of the next length of the workpiece. The shuttle vise assembly then clamps the workpiece, the stationary vise releases the workpiece, and the shuttle vise is displaced an equal distance toward the saw blade cutting stretch to move the workpiece into a cutting position. The stationary vise assembly then clamps the workpiece when it is in the cutting position, and both vises hold the workpiece while it is being cut.
Automatic or shuttle vises which are reciprocable along guides or tracks on a vise bench to automatically position the workpiece for a series of outs at appropriate positions are broadly well known in the art. Such a production shuttle vise assembly is shown, for example, in my U.S. Pat. No. 4,117,756.
One of the problems which is commonly encountered in connection with production sawing of workpieces using a band saw apparatus, and particularly in connection with production sawing of relatively large diameter lengths of bar stock, is the tendency of the clamping forces exerted by opposed jaws of the vise assembly to push the bar stock up and out of the vise assembly. This tendency toward upward displacement of the workpiece occurs because large diameter round stock engages the faces of the vise jaws toward the top of the vise faces. Conventional vise jaws usually will be urged toward each other at a position below the position at which large diameter round stock is gripped by the vise faces, which combines with the clearances inherent between the vise jaws and the vice ways to tend to push the workpiece up and out of the vise.
Additionally, as the length of the workpieces increases, warping of the workpieces along their longitudinal axes also creates vise alignment problems. Bar stock which is warped along its longitudinal axis is generally usable, since the bar stock will often be cut into short enough lengths that the warp is insignificant. During production sawing, however, it is difficult to rigidly clamp a warped workpiece in two locations, the shuttle vise and the stationary vise, while still holding the workpiece in substantially perpendicular alignment with respect to the cutting plane of the saw blade.
Both shuttle and stationary vises must include structures which permit the lateral adjustment of the stroke or clamping range of the vises. Vise assemblies are known in the art which have adjustable clamping strokes. For example, U.S. Pat. No. 3,759,504 teaches a vise assembly including a fixed jaw and a movable jaw for clamping a workpiece. The movable jaw is adjustably mounted on a toothed rack, and adjustment of the working range of the clamping stroke of the movable jaw is effected by means of a toggle mechanism. U.S. Pat. No. 3,820,773 teaches a vise assembly for feeding a workpiece into a cutting position on a cutting device, such as a band saw apparatus, wherein a pivoted lever is attached to the movable jaw, and the pivoted lever engages the top of a toothed rack. The rack is urged toward the workpiece and pushes the movable jaw toward the workpiece by means of a pivoted lever. The pushing mechanism for the rack is also coupled to a vertically movable roller which is moved up to engage and advance the workpiece.
Prior art adjustable stroke vise assemblies do not adequately overcome the problems outlined above, particularly problems related to properly positioning a shuttle vise assembly to accommodate a warped workpiece, such as may occur in a long section of bar stock, while maintaining the workpiece in a cutting position in substantially perpendicular alignment with respect to the saw blade cutting stretch. Prior art adjustable vise assemblies also do not satisfactorily overcome problems related to rigidly clamping workpieces between opposed jaws of the vise assembly to prevent the workpieces from being pushed up and out from the cutting position.
Accordingly, it is an objective of the present invention to provide a vise assembly which is particularly suitable for use with band saw apparatus for production cutting of workpieces.
It is still another objective of the present invention to provide a shuttle vise assembly for adjusting the opposed vise jaws of the shuttle vise to accommodate a warped workpiece while maintaining the workpiece in a cutting position in substantially perpendicular alignment with respect to a saw blade cutting stretch.
It is yet another objective of the present invention to provide a vise assembly including improved clamping means for preventing workpieces from being pushed up and out from the cutting position between opposed jaws of the vise assembly.
It is another objective of the present invention to provide an improved method for rigidly clamping a workpiece between opposed jaws of a vise assembly.
It is still another objective of the present invention to provide an improved method for adjustment of generally opposed jaws of a vise assembly as a unit while keeping them parallel to the workpiece receiving channel to accommodate and substantially rigidly clamp warped workpieces.